This disclosure generally relates to multi-deck aircraft and, more particularly, relates to multi-deck airplanes having a tube-type fuselage and a mid-level wing that passes through the fuselage.
Advanced designs for high-capacity commercial and military airplanes require operating efficiency combined with reduced emissions and low noise. In order to meet these requirements, super-high bypass ratio jet engines, such as geared turbo fan or open-rotor jet engines may be used. These engines typically employ larger-diameter engine fans, rotors and/or nacelles which, because of their size, may place design constraints on other components of the airplane. For example, larger-diameter engines mounted beneath the primary lifting wing on the airplane may require excessive inboard wing shear and associated large weight penalties on a low-wing airplane configuration, or alternatively may require that the wing be positioned at a higher level on the fuselage in order to provide sufficient ground clearance beneath the engines. This higher placement of the wing on the fuselage may in turn place constraints on the configuration of payload-carrying decks within the fuselage.
Traditional commercial aircraft have been designed around a simple circular tube to carry passengers and cargo and a wing. The traditional airplane configuration places all passengers on one deck and cargo on a lower deck. To configure an airplane in the traditional approach, a passenger count and seat width dimension is decided and then the airplane is wrapped around this seat arrangement. The close wrapping of cargo and passengers at the same time is not a traditional approach.
When designing a new airplane, many other factors need to be considered. The world airplane market is becoming increasingly sensitive to fossil fuel burn, which can be measured by the airplane specific fuel consumption and emissions. A direct correlation to fuel burn can be drawn to the airplane wetted area: the smaller the wetted area, the lower the drag on the airplane. Aircraft noise is also becoming more of an issue, especially during airport operations and during approach and departure. Furthermore, the commercial aviation industry has traditionally surveyed North America and the European markets, where the air transportation infrastructure can be crowded, and one of the parameters to gauge an aircraft concept is the footprint size of the airplane. A smaller footprint size for a given passenger capacity is desirable. In addition, as labor becomes more expensive worldwide and airlines rely on revenue cargo operation for profits, containerized cargo assists airlines not only turn the airplane quicker between flights, but also helps airlines lower labor costs and potential personnel injury issues. Faster airplane turn times have a great value to an airline. The ability to utilize dual boarding and departure operations can help decrease airplane turn times. Most airplanes do not allow for dual deck utilization for passengers and containerized cargo.
Accordingly, there is a need for a mid-wing multi-deck airplane that allows the use of high-efficiency, large-diameter engines with minimal adverse impact on the capacity and layout of payload-carrying decks and that has a configuration which allows the wetted area and footprint size to be optimized for a particular payload capacity.